Hydrophone



Dec. 9, 1947. R. BLACK, JR, El" AL HYDROPHONE 2 Sheets-Sheet 1 FiledDec. 8, 1942 FIG.

FIG: 3 30 R BLACK JR;

M W A. SHANN wvmmns' I 1947. R. BLACK, JR., ET AL 2,432,083

HYDROPHONE Filed Dec. 8, 1942 2 Sheets-Sheet 2 FIG. 6

1?. Buck, JR. EEROMA/VOW 0. A. SIM/WV hrrmir INVE N 7URS.

l rier member as to Patented 9, 1947 ICE HYDROPHONE Robert Black, Jr.,

South Orange, Frank F;

Romanow, Summit, and Oscar A. Shann, Short 1 Hills, N. J.,

oratories, Incorporated, v poration of New .York

. 'ApplicationDecember 8, 1942, Serial No. 468,246

6 Claims. (01117-386) This invention relates to submarine signaldetecting devices or hydrophones.

An object of the invention is to improve the structure and the operatingcharacteristics of hydrophones.

In accordance with the invention, a hydrophone or submarine signaldetector may comprise a transducer unit so supported on a frame orcarfunction on the inertia, principle, the carrier member being of suchshape and resiliency as to make a substantially tight fit with asubstantial area of the inner surface of a thin-walled hermeticallysealed and water-tight container or enclosure. The outer surface of thecontainer is covered with a substantially uniform thickness of rubbermolded around the container. This general arrangement involvesstructural simplicity and ruggedness, protection of the mechanical andelectrical parts against corrosion, a low order of distortion andattenuation in the signal transmission from the water to the transducer'unit, and adaptability to quantity manufactors with reproducibleresponse-frequency characteristics.

A more complete understanding of this invention will be obtained fromthe detailed description that follows taken in conjunction with theappended drawings, wherein:

Fig. 1 is a side view'of a hydrophone embodying the invention;

Fig. 2 is an end view of the device of Fig. 1;

Fig. 3 is an enlarged side View, partly in section and partly brokenaway, of the electromechanical assembly included in the device of Fig.1;

Fig. 4 is an end view of the assembly of Fig. 3;

Fig. 5 is a sectional View of the assembly of Fig. 3, along the line 55thereof;

Fig. 6 is a sectional view along the line 6--6 of Fig. '7, Fig. 7 andFig. 8 beingv plan and side views, respectively, of the transducer unitassembly included in the str cture illustrated by Fig. 3; and

Fig. 9 is an enlarged perspective view of the transducer unit includedin the hydrophone.

With reference to the drawings, the hydrophone is seen to comprise atransducer unit I included in an, assembly ll within a water-tight andhermetically sealed enclosure or container l2 that is completely coveredor coated by a substantially uniformly-thick layer of rubber l3.

The transducer unit assembly will be best understood by particularreference to Figs. 3 and to 9.

The magnetic system of the transducer unit may be substantially the sameas that of the telephone receiver of M. S. Hawley Patent 2,202,906 ofJune 4, I940. It comprises an armature IS, a pair of bar permanentmagnets IS, a pair of U-shaped pole-pieces l1, current coils l8surrounding the inner arms of the pole-pieces,

assignors to Bell Telephone Lab- New York, N. Y., a cor- 2 I and a.spider member l9 providinga mechanical stillness member coupling thearmature to the other components of the magnetic system, the

' Dole-pieces and magnets being welded together and the spider memberbeing fastened to the pole pieces by screws 20, all of which isdescribed in greater detail in the aforementioned Hawley patent. In thepresent arrangement, the magnetic system is fastened to the planarportion 2| of a D-shaped frame member or chassis 23' by fastening means22. whereby, since the armature is soldered to the spider member, thearmature, the other components of the magnetic system as a group, andthe chassis are adapted for relative movement on vibration, for example,of the chassis. The planar portion of the frame member contains anappropriately shaped aperture 24 for the armature, and additionalapertures through which insulated Wires or leads 25 may be drawn forelectrically connecting theends 2B of the current coils with terminalson the centainer i2. The frame member-may be of a nonmagnetic metal.such as brass, and, except for its planar portion 2!, substantiallyannular in crosssection. The curved portion of the frame member isdivided intoa pair of substantially similar but opposed arcuate portions2! by a slot or slit 28 extending along the length of the frame memberat a location substantially intermediate the junctions of the curvedportion with the planar portion. When the transducer unit assembly isoutside of the container l2, the arcuate portions 2'! are sprung apart,for example, as illustrated by Fig. 6. When the assembly is inside ofthe container, the portions 21 are forced together, as i]- lustrated byFig. 5, the tendency of the arcuate portions to restore themselves tothe condition of Fig. 6 resulting in an exceptionall tight fit betweenthe frame member and a substantial area of the inner surface of thecontainer, to provide an excellent vibration transmission relationshipbetween the container and the frame member and, therefore, thetransducer unit. In slidably inserting the assembly I! in the containerduring manufacture of the hydrophone, the arcuate portions 21 would beforced together sufficiently for the purpose.

The container l2 comprises a thin-walled, metallic envelope 3|]substantially cylindrical in shape, formed with a closed end portion 3|of slightly reduced diameter and an open end portion provided with anoutwardly flaring annulus 32. The latter end portion may be closed by aclosure assembly 33 having a central opening closed by a disc 34 ofinsulating material, a shoulder portion 35 that may. be ring welded tothe annulus 32 and an annular skirt 35 bent over portions 31 of whichhold a terminal plate 38 of insulating material securely within theclosure assembly. The disc 34 may be cemented in position and supports apair of connector wires 39 electrically connecting the leads 25 with theterminals 40 on the plate 38. The conductors 4| of the v cable 42 forconnecting the hydrophone with suitable electrical equipment (not shown)in a vessel or on shore are brought into the container through suitableapertures in the plate 38 and terminated at the terminals 40. All themetallic joints of the container assembly are water and air tight, thesealed-off tubingMlbjeing the remnant of a tube extending through thedisc 34 for introducing, prior to the' addition of the plate 38 to theciintainer assembly, air at substantial pressure to test the hermeticcharacter of the seals. The envelope 30 and all but the disc. 34 of theclosure assembly may be of a magnetic material, such as steel. A disc42' of similar material, provided with suitable apertures forthe'connectors 39 may be inserted in the closure assembly opening overthe disc 34 to provide a closed magnetic shield aro'und the'transducerunit to protect it against the effect of magnetic fields developedduring the welding operations as well as against the effect of magneticfields that may be present in the environment in which the hydrophonemay be used.

During the assembly of the hydrophone, after the transducer unitassembly is inserted in the envelope 30, the latter may be forcedslightly into the reduced diameter portion 3| to ensure rigid couplingbetween th frame member and the envelope. The "air and water-tightcharacter of the seals and joints... of the container may be tested,prior to securing the terminal plate in position, by use of air underpressure introduced through the tubing 44 while the container is heldunder water or in carbon tetrachloride. The rubber layer [3 is moldedaround the container and the container end of the cable 42 as the laststep of the manufacture. The responsefrequency characteristic of thedevice may be measured at intervals to ascertain that it remains withinpermissible limits before the next assembly step.

In use, the hydrophone is submerged in water, for example in a lake, ariver or the sea, at the end of a suitable suspension, or may beincluded with a number of similar devices at spaced intervals in acable, for example, extending across the mouth of a river or theentrance to. a harbor. Submarine signal waves or other underwaterdisturbances in the audio frequency range will cause the hydrophone tovibrate. These vibrations produce relative movement between the springcoupled armature and .the remaining structure ofthe transducer lunitmagnetic system, whereby the variationin the reluctance of the magneticcircuit induces currents in the coils on the pole-pieces that correspondto the signal waves or disturbances. These currents are led over theconductors of the cable to suitable electrical indicating or translatingequipment in a vessel or at a shore station. The outer rubber layerprotects the container against the corrosive effects of the water. thethin-walled envelope efficiently transfers vibration to the D-shapedframe member and the latter effectively transfers the disturbance tothe; transducer unit.

Although the invention has been disclosed with reference to a specificstructure} it is evident that modifications therein may be made by theskilled 4 V in the art without departing from the invention.

What is claimed is:

1. A hydrophone comprising .a water-tight hermetically sealedcylindrical container, a spring metal frame member adapted to be whollyincluded within said container, said frame member being 'slidablyinsertable in said container and expans'ible therein to make a tight fitwith a substantial area of the inner surface of the latter, and anelectromechanical transducer unit mounted on and supported solely fromsaid member so as 'to respond to vibrations transmitted to said framefrom said container.

frame member is substantially D-shaped in sec- 3. The hydrophone ofclaim 1 in which said frame member is substantially D-shaped in sectionwith the curved portion of the D-shaped frame in close contact with .theinner cylindrical surface of said container and the transducer unitsupported from the planar portion of the frame member. I

4. The hydrophone of claim 1 in which said frame member is substantiallyD-shaped in section, the curved portion of the D-shaped frame havingapproximately the same radius of curvature as the cylindrical container,said frame having a slot extending along the length of its curvedportion.

5. The hydrophone of claim 1 in which said frame member is substantiallyD-shaped in section, the curved portion of the D-shaped frame havingapproximately the same radius of curvature as the cylindrical container,said frame having a slot therein extending along the length of itscurved portion approximately intermediate the junctions of the planarand the curved '45 portions of the member.

6."The hydrophone of claim 1 in which said frame member is substantiallyD-shaped in section, the curved portion of the D-shaped frame havingapproximately the same radius of curva- 50 ture as the cylindricalcontainer, said frame having a slot extending along the length of itscurved portion approximately intermediate the junctions of the planarand curved portions of the member, the transducer unit being supported 5from the planar portion of the member.

ROBERT BLACK, JR. FRANK F. ROMANOW. OSCAR A. SHANN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number 2. Thehydrophone of claim 1 in which said-

